2. Add food colouring, this should make the water quite dark to contrast the oil

3. Add the antacid- this can be done in sections to prolong the excitement

4. Shine the flashlight at the bottle

And there you have it, a lava lamp! You’ll have to add tablets to maintain the lamp but seal the bottle and you can keep the mixture forever.

The Science

Oil is made up of lipid molecules. Imagine these molecules are pin shaped with the head hydrophilic (attracted to water) and the tail hydrophobic (repelled by water). Therefore they don’t mix and when put together they separate into layers. At the interface these lipid molecules line up so that the hydrophilic heads face water and the hydrophobic tails are away from water. The water will be at the bottom as water is more dense than oil, meaning that the weight of a volume of water is more than the weight of the same volume of oil. So why do blobs form when you add the tablet?

When the tablet dissolves it creates gas, carbon dioxide, this is seen as fizzing. This gas attaches to water causing the water to float to the top, through the oil. The gas then dissipates in air leaving the water to fall back to the bottom.

Christmas Party Trick

You don’t need a bottle, it can be any container. Why not try a wine glass at the Christmas table and entertain all the family. Just make sure no one tries to drink it, the lava inside may not be hot but we assure you it won’t taste good!